Flotation of spodumene



United States PatentO FLOTATION OF SPODUMENE Fred H. Buuge, La Grange, 111., assignor to Armour and Company, Chicago, 111., a corporation of Illinois No Drawing. Application June 23, 1952, Serial No. 295,123

6 Claims. (Cl. 209-166) This invention relates to the processing of mineral ores and more particularly to the flotation recovery of spodumene.

Spodumene ore which is an important source of lithium, is relatively rare in occurrence. Because of its relative scarcity, there is considerable interest in efficient methods of recovering spodumene from available sources.

Ordinarily spodumene is found in association with feldspar, mica, quartz and small amounts of other minerals, particularly iron-bearing minerals. In order to obtain a useful spodumene concentrate, it is necessary to effect a selective separation of the spodumene from the associated minerals.

Heretofore it has been found expedient to isolate spodumene by froth flotation employing as a collecting agent a fatty acid or a fatty acid soap. By this method the desired spodumene is obtained in the flotation layer and the unwanted minerals are recovered in the tailing. This method has a limited use only and is applicable only to unweathered ore. Where considerable weathering has occurred, the spodumene which has weathered is formed as a coating on the other associated minerals. The coating of the minerals with spodumene is ordinarily so extensive that, when a flotation separation is attempted, all of the spodumene ore, including the minerals coated with weathered spodumene, are floated alike. Consequently, flotation of weathered spodumene ore with a soap collector fails to provide a separation of spodumene from its associated minerals.

I have now discovered a method of concentrating spodumene ore which is effective for weathered ores, unweathered ores, and mixtures thereof. In attempting to separate traces of iron from a weathered ore containing spodumene, feldspar, quartz, and iron-bearing materials in a circuit containing an amount of sulfonated oil collector, I have made the discovery that a highly selective separation of spodumene is had. This was surprising since it was expected that the iron would float and that the spodumene would be depressed along with feldspar and quartz. It was even more surprising that substantially all of the spodumene floated along with the traces of iron while at the same time the quartz and feldspar were depressed and were not carried to the flotation layer by entrained spodumene particles.

It is important in carrying out the present invention to employ a finely divided ore. The ore should be ground to 48 mesh or finer for more satisfactory results, and preferably to 65 mesh and finer. It is a feature of the present invention that the raw ore feed need not be specially treated to counteract the efiects of weathering prior to grinding and conditioning.

The present invention may be illustrated in connection with a specific example of the separation of spodumene from ore obtained in the Kings Mountain, North Carolina, region. The ore, containing 3% lithium (LiaO), is ground in a ball mill to 48 mesh. The'ground ore is then pulped at 25% solids and deslimed by any suitable 2,748,938 Patented June 5, 1956 ice method such as hydraulic classification. A small amount of a dispersing agent such as Daxad 11 (1.65 pounds per ton of ore) may be employed to facilitate the desliming of the ore pulp.

Following desliming, the ore is conditioned for 2 to 3 minutes at 70 to solids in a circuit containing, per ton of ore processed, 3.6 pounds sulfuric acid, 2.21 pounds of sodium salt of petroleum sulfonate (Reagent 825, American Cyanamid'Company), and 1.28 pounds of kerosene. A frothing agent such as pine oil in the amount of 0.16 pound per ton may also be employed. Subsequently, the conditioned ore is diluted to 25 solids and subjected to froth flotation at pH 3 to 4 for 2 minutes. The flotation layer which contains enriched spodumene analyzes as 7.10% LizO.

In carrying out the present invention, it is desirable to preliminarily deslime the ground ore. Desliming ordinarily results in a more selective separation. Such desliming, however, is an optional procedure and may be omitted.

The hydrogen ion concentration in the conditioning and flotation circuits may be varied considerably. A separation may be obtained in an acid circuit and, for optimum results, the pH should be from 1 to 2 in the conditioning circuit, and from 3 to 4 in the flotation circuit. Since the present method does not depend for its success on the choice of any specific acid material, any suitable acid materials may be employed to provide the degree of acidity desired. For example, I may use sulfuric, hydrochloric, and other like acids. Sulfuric acid is especially useful and is ordinarily preferred from the standpoint of cost.

Various sulfonated oleaginous materials may be employed as collecting agents in connection with my invention. These may be obtained by sulfonating any of the oils (preferably readily available oils) which are substantially insoluble in water. As specific examples of oils which in sulfonated form are suitable, may be mentioned, glyceride oils, such as fish oils, vegetable oils, animal oils, fatty acids derived from glyceride oils or from tall oil or fractions of tall oil, petroleum oils such as kerosene, fuel oil, and the like. It will be noted that the oil employed may contain any of various hydrophobic groups such as fatty acid, resin acid, abietic acid, hydrocarbon groups of the paraffin, olefin and acetylene series, aralkyl, and aromatic groups. The compounds suitable as collectors in accordance with the present invention will be referred to herein as sulfonated oils, and it will be understood that this designation applies to both solid and liquid materials. The sulfonated oils are characterized as being soluble in oil and substantially insoluble in water, and may be dispersed in water to form oil-in-water emulsions. The sulfonated oils may be employed in free sulfonic acid form or in the form of a salt. For example, the mahogany sulfonates (the sodium salts of petroleum sulfonates) are especially useful. Also, the oil may contain one or more sulfonate groups for each oil molecule. Small amounts of the sulfonated oils are effective in providing the desired collecting action. Usually from 1 to 2 pounds of sulfonated oil per ton of ore will be satisfactory. According to the preferred practice, the sulfonated oil collector is dissolved in an amount of unsulfonated oil, such as fuel oil, and the solution is dispersed in the conditioning circuit. Heat may be employed to facilitate the solution and dispersion of the collector. The unsulfonated oil, which may be any waterinsoluble (e. g. hydrocarbon) oil, serves to extend the collector and increases the effectiveness of the collecting action. Furthermore, since the unsulfonated oil is relatively inexpensive, a saving in the cost of reagents is obtained. v In charging the collector into the circuit, there should be sufficient mixing to provide in the aqueous pulp a dispersed oil phase containing the sulfonated oil and, when used, the unsulfonated oil.

While the collecting action of the sulfonated oils with respect to spodumene is not fully understood at present, it has been established that they have a preferential ailinity for spodumene (as distinguished from the unwanted associated minerals) whereby the spodumene particles are contacted and provided with a hydrophobic coating surrounding the individual particles. The unsulfonated oil contained in the circuit in turn attaches to the hydrophobic coating in a protective film, enclosing the sulfonate-coated spodumene particles. The particles thus conditioned are provided with a surface to which air bubbles in the flotation circuit preferentially attach. The unwanted minerals which remain unaifected by the collecting agents do not attract airbubbles and therefore have a tendency to settle out in the tailing.

The present invention may be practiced with any of the apparatus suitable in connection with froth flotation. In particular, any flotation apparatus which provides agitation and aeration of the pulp will be adequate.

The pulp density in the conditioning and flotation circuits may be varied widely. In the conditioning circuit 60 to 85% solids is preferred and 70% solids is considered an optimum condition. In the flotation circuit the solids may run as high as 40%. A pulp density is especially effective for flotation.

The present invention is applicable to any spodumene ore and may be practiced equally well in connection with both weathered and unweathered ores. In addition to spodumene, the ore may contain associated minerals such as mica, feldspar, quartz, minor amounts of iron-bearing minerals, etc.

Since considerable mica is contained in certain spodumene ores, it is desirable in some cases to remove the mica content prior to flotation of the spodumene. If not removed, the mica floats with the spodumene, thereby causing a less selective recovery of spodumene. The mica may be conveniently removed by flotation with any suitable cationic collector such as short-chain amines or small amounts of long-chain amines and amine salts. In this connection, I have found it satisfactory to proceed as follows: Spodumene ore containing mica is deslimed as set forth above and conditioned at 25% solids in an acid circuit containing, per ton of ore; 3 pounds of sulfuric acid, 0.04 pound of tallow amine acetate, and 0.16 pound of pine oil or other suitable frothing agent. The tallow amine acetate (Armac TD, Armour and Company) referred to is the acetate salt of the amines derived from tallow including hexadecylamine, octadecylamine, octadecenylamine, etc. After conditioning for A minute the mica is floated away and the mica free ore pulp is processed further in accordance with the method of separating spodumene indicated above. Preferably the flotation of mica is accomplished at 25 solids and at a pH of from 3 to 5.

According to the preferred practice, a frothing agent such as pine oil is employed. The use of a frothing agent, however, is optional and may be omitted. Satisfactory recoveries of spodumene are obtained without the use of a frothing agent.

The following specific examples, in which Kings Mountain, North Carolina, ores are employed, serve to illustrate the recovery of spodumene in accordance with the present invention.

Example I The ore is ground to 65 mesh in a rod mill and hydraulically deslimed after dispersing the slimes with, 1.65 pounds per ton of Daxad 11. The deslirned ore is then passed to the conditioning circuit containing, per ton of ore, 3.30 pounds of sulfuric acid, 0.03 pound of Armac TD (tallow amine acetate), and 0.16 pound of pine oil, and conditioned at 25 solids and pH 4.2 for A minute. Subsequent to conditioning, the ore is floated at 25% solids (pH 4.2) for 2 minutes. The flotation layer containing mica is separated and the mica-free pulp is conditioned for 2 /2 minutes at solids in a circuit containing 3.30 pounds of sulfuric acid, 0.08 pound of pine oil, 1.65 pounds of Reagent 825, and 0.80 pound of kerosene. Following conditioning, 0.60 pound per ton of sulfuric acid is added and the pulp is diluted to 25 solids and floated at pH 5.1 for 2 minutes. The flotation layer consisting largely of spodumene is recovered from the circuit which contains largely feldspar and quartz. The metallurgical results are as follows:

- Assay Recovery Weight Product Percent Piriggut Pgjegnt Slimes 13.3 3g 18.; i 2713 5150 6017 56.7 1. 24 28.4

Example II The spodumene ore containing mica is ground to -65 mesh in a ball mill and hydraulically deslimed. The deslimed ore is passed to the conditioning circuit containing, per ton of ore, 3.30 pounds of sulfuric acid, 0.03 poundof Armac TD and 0.16 pound of pine oil, and conditioned at 25% solids for A minute. The flotation layer containing mica is separated and the mica-free pulp is further conditioned for 3 minutes at 70% solids and pH 2 in a circuit containing 3.30 pounds of sulfuric acid, 0.08 pound of pine oil, 1.65 pounds of Reagent 825, and 1.60 pounds of kerosene. Following conditioning, the pulp is diluted to 25 solids and floated for 2 minutes at pH 3.9. The flotation layer, which consists largely of spodumene, is removed.

The metallurgical results are as follows:

- Assay Recovery Weight Product Percent Pirfieont Pigriilagnt 15. 5 2. 25 13. 5 2. 6 1. 08 l. 2 2S. 9 5. 40 63. 7 53. 0 1. 0 21. ti

Example III Spodumene ore containing mica is ground to 65 mesh in a steel rod mill and is deslimed. The deslimed ore is passed to the conditioning circuit containing, per ton of ore, 3.4 pounds of sulfuric acid, 0.10 pound of Armac TD and 0.16 pound of pine oil, and conditioned at 25% solids for /4 minute. The conditioned ore is then floated for 2' minutes at pH 2.8, and the flotation layer containing mica is separated.

The mica-free pulp is further conditioned for 3 minutes at 70% solids and pH 2 in a circuit containing, per ton of ore, 3.4 pounds of sulfuric acid, 0.32 pound of fuel oil, and 2.0 pounds of mixed sulfonated fatty acids obtained by sulfonating with fuming sulfuric acid a mixture of oleic acid (by weight, 46% linoleic acid (39%), linolenic acid (3%), and resin acids (calculated as abietic acid, 12%). to 25 solids and floated for 2 minutes at pH 3.0. The flotation layer, which consists largely of spodumene, is recovered.

In determining the metallurgical results, a sink test is used in which representative samples of the material recovered in the flotation layer are dispersed in a test liquid having a specific gravity intermediate that of spodumene and feldspar. In such a liquid the feldspar tends to float while the spodumene sinks. The weight distribution of material thus tested serves as an indication of the per- Following conditioning, the pulp is diluted centage of spodumene contained in the original sample.

The metallurgical results are as follows:

While in the foregoing specification specific embodiments of the present invention have been set forth in considerable detail, such detail may be varied widely by those skilled in the art without departing from the spirit of my invention.

I claim:

1. In a process for the concentration of a spodumenebearing ore without chemical treatment to prepare the surface thereof, the step of subjecting said chemically untreated ore to froth flotation in the presence of a sulfonated oil to cause selective flotation of spodumene.

2. In a process for the concentration of a weathered spodumene-bearing ore without chemical treatment to counteract the eifect of weathering, the step of subjecting said weathered ore to froth flotation in the presence of a sulfonated oil to cause selective flotation of spodumene.

3. In a process for the concentration of spodumene from a weathered spodumene-bearing ore without chemical treatment to counteract the efiect of weathering, the

step of subjecting an aqueous acid pulp of finely ground spodumene ore to froth flotation in an acid circuit containing a water dispersible sulfonated hydrocarbon.

4. A process according to claim 3 wherein said pulp contains spodumene ore particles of 48 mesh size and smaller.

5. A process according to claim 4 wherein a mahogany sulfonate is employed.

6. In a process according to claim 2 wherein the weathered spodumene-bearing ore contains mica, the additional step of initially separating the mica therefrom by a froth flotation employing an agent selective to the mica.

References Cited in the file of this patent UNITED STATES PATENTS 2,303,931 Greene et a1. Dec. 1, 1942 2,385,054 Booth et a1 Sept. 18, 1945 2,433,258 Booth at al Dec. 23, 1947 2,466,987 Herkenhoif Apr. 12, 1947 2,483,192 Gieseke Sept. 27, 1949 OTHER REFERENCES Bureau of Mines Report of Investigations 3892, June Engineering and Mining Journal, June 1939, vol. 140, No. 6, pp. 49-S1. (Copies available in Scientific Library.)

Taggart, Handbook of Mineral Dressing, 1945 by J. Wiley & Sons, New York, Sec. 12, p. 127. (Copy in Div. 55.)

Bureau of Mines Report of Investigations 3328, pp. 104-111. (Copy in Scientific Library.) 

1. IN A PROCESS FOR THE CONCENTRATION OF A SPODUMENEBEARING ORE WITHOUT CHEMICAL TREATMENT TO PREPARE THE SURFACE THEREOF, THE STEP OF SUBJECTING SAID CHEMICALLY UNTREATED ORE TO FROTH FLOTATION IN THE PRESENCE OF A SULFONATED OIL TO CAUSE SELECTIVE FLOTATION OF SPODUMENE. 